Emergency braking means for material handling elevator



United States Patent 72] Inventor William E. Riedner Battle Creek, Michigan [2]] Appl. No. 755,004

[22] Filed Aug. 23, 1968 [45] Patented Dec. 1, 1970 [54] EMERGENCY BRAKING MEANS FOR MATERIAL HANDLING ELEVATOR 18 Claims, 4 Drawing Figs.

[52] US. Cl 187/87, 187/17, 187/95 [51] Int. Cl B66b 5/16 [50] Field ofSearch 1.87/81-87 [56] References Cited UNITED STATES PATENTS 501,396 7/1893 Albro 187/87 922,452 5/1909 Burgan 187/83 1,031,470 7/1912 Sanna.... 187/87 1,277,763 9/1918 Silva 187/87 2,403,333 7/1946 Bjerke 187/82 2,513,224 6/1950 Woodward 187/81 FOREIGN PATENTS 1,081,635 5/1960 Germany Primary Examiner-Harvey C. Hornsby Attarneysl(enneth C. Witt, John C. Wiessler, Robert H.

Johnson and Reginald J. Falkowski ABSTRACT: A material handling and stacking vehicle is horizontally movable along a track and has a vertically movable elevator for carrying materials. An emergency braking device within a vertical channel is attached to the elevator and operates to prevent falling of the elevator if a support chain breaks. The braking device has an actuator bar held in place by the tension of the support chain against the force of a biasing spring. If the support chain breaks, the tension decreases and the biasing spring moves the actuator bar against the cam surfaces of two serrated shoes. The actuator bar pushes against the cam surfaces and rotates the serrated shoes to engage the serrations with the side of the vertical channel and thereby support the elevator. A reset pin is positioned to act against the cam extensions on the shoes to return the shoes to normal operating position upon support of the load by the support chain.

Patented Dec. 1, 1970 Sheet L of 2 INVILV/UR WILLIAM E. RIEDNER BY j FlG. I

ATTORNEY Patented Dec. 1, 1970 Sheet y'kwm LWIgN/OR WILLIAM E. RIEDNER y} 7 W- ATTORNEY EMERGENCY BRAKING MEANS FOR MATERIAL HANDLING ELEVATOR This invention relates to braking devices for elevators, particularly to emergency mechanical braking devices that operate upon loss of normal elevator support.

In material handling systems having stacking vehicles movable within aisles and chain supported and driven elevators for moving material vertically and laterally into and out of bins, it is necessary to have safety devices to prevent falling of the elevator if the support chain should break. These devices should be simple and reliable and adaptable to a system having a laterally movable platform on the elevator. It must, therefore, be operable within a limited space without unduly interfering with the complicated structure used in stacking vehicle construction and operation.

With this invention a simple and effective mechanical device senses the tension of the chains supporting the elevator and operates to prevent the elevator from falling if a support chain breaks by responding to a decrease in support chain tension. The device is simple in construction and can be utilized alone or in conjunction with other safety devices to provide maximum operational safety.

The objects and advantages of the invention will be apparent from the following detailed description.

FIG. 1 is a perspective view of a stacking vehicle having an emergency braking device according to this invention;

FIG. 2 is a side view of the braking device;

FIG. 3 is a top view of the braking device; and

FIG. 4 is a front cross section view of the braking device.

Referring to FIG. 1 a stacking vehicle for use in a material handling and storage system is moved along a path over rails 12 by any known moving means (not'shown) on wheel 13 and comprises an elevator 15 having a laterally movable support platform 16, means for raising and lowering the elevator on the stacking vehicle including a driving means (not shown) for driving support chains 17 and 18, means for laterally moving the platform (not fully shown), and two emergency braking assemblies, one on each side of elevator 15.

Emergency braking assemblies 21 and 22 each comprise vertical channels 31 and 32 located adjacent the vertical path of elevator 15, and emergency braking devices 19 and mounted on horizontal support members 33 and 34, respectively, which are part of elevator 15. Referring to FIGS. 2, 3, and 4, braking devices 19 and 20 are similar in construction and braking device 20 will be described in detail. Braking device 20 comprises a pair of rotatable shoes 51 and 52 having cam surfaces 510 and 52a and offset serrated portions 53 and 54, respectively, that are located within channel 32; an operating means for appropriately rotating the shoes to engage the side of channel 32 upon decrease in chain tension indicating that the chain has broken and is no longer supporting the elevator; and a signal means for producing a signal indicating the breaking of the chain.

The rotatable shoes are mounted within the channel and have serrated portions or edges 53 and 54 that upon appropriate rotation engage the respective side of channel 32. The rotatable shoes are rotated in opposing directions to move upwardly relative to the channel sides to utilize the downward force of the elevator and insure that the serrated edges dig into the channel and support the elevator upon breaking of the chain.

The operating means comprises a connecting means having two positions, one effecting rotation of the rotatable shoes to engage the channel and the other to effect rotation of the shoes to be free of the sides of the channel; a positioning means for maintaining the shoes in a rotated position at which the serrated portions are free of the channel; and a biasing means for moving the shoes to a position engaging the channel upon decrease in tension of the chain below a preselecte level indicating that the chain has broken.

The connecting means comprises a housing 35 connected to elevator 15 that has a lost motion slot 37 for receiving a connecting pin 38 and two pivot pins 47 and 48 adapted to receive rotatable shoes 51 and 52, respectively, and a connecter assembly. The connecter assembly comprises a connecter 36 connected with connecting pin 38 to housing 32 through lost motion slot 37, which provides limited movement of connecter 36, and an actuator bar 39 operably engageable with connecter 36 at a recess 41 in the connecter.

The positioning means comprises'a linkage means such as a chain connecter linkage 59 extending between connecter 36 and chain 18, cam extensions 55 and 56 on shoes 51 and 52, and a reset pin 58 engageable with the cam extensions to move the shoes to nonnal operating position upon restoration of appropriate tension, or during normal operation, through chain connecter linkage 59 between support chain 18 and connecter 36.

The biasing means comprises an actuator bias spring 42 located within a spring housing 43 and connected through a spring seat 44 and actuator adjustment assembly 45 that biases actuator bar 39 downwardly through a lip 50 on the actuator bar. The biasing spring is adjusted and selected to provide sufficient tension to move the actuator bar downwardly so that a shoe engaging lip 57 engages shoes 51 and 52 at cam surfaces 51a and 520 respectively and rotates them outwardly to engage the channel sides.

The signal means comprises a switch assembly 60 mounted to have a switch 60 controlled by position of connecter pin 38. Upon movement of connecter 36 relative to housing 35 through the force of biasing spring 42, switch 61 is moved to operate a circuit to indicate the operation of the braking device and initiate any electrically controlled functions necessary to stop operation of the elevator system in any known manner.

In operation of the emergency braking as a result of the breaking of support chain 18, braking device 20 responds to the decrease of tension on support chain 20 through chain connecter linkage 59 by having actuator biasing spring 42 pull actuator bar 39 downwardly. Shoe engaging lip 57 is thereby pulled against surfaces 51a and 520, respectively shoes 51 and 52 to rotate the shoes and move serrated portions 53 and 54, which are offset on a cam surface relative to the channel sides and the pivot pins, against the sides of vertical channel 32. The downward motion of the elevator assists in rotating the serrated portions causing the serrated edges to dig into the channel surface and prevent the elevator from dropping.

Since there are two brake devices 19 and 20, either operates upon the breakage of its respective support chain. The operation of either braking device operates switch 61, or the comparable switch in device 19, and stops further movement of the system. If both chains break, both brake devices operate to support the elevator.

Upon repair or recovery of chain tension and return of support of the elevator to support chain 18, for example, chain connecter linkage 59 moves connecter 36 upwardly to raise actuator bar 39 upwardly against the force of biasing spring 42. Reset pin 58 on actuator bar 39 is moved against the under portion of cam extensions 55 and 56 and the shoes are rotated and freed from the side surfaces of channel 32.

While this specification contains a written description of the invention and the manner and process of making and using it and sets forth the best mode contemplated of carrying out my invention, there are many variations, combinations, alterations and modifications of the invention that can be made within the spirit of the invention and the scope of the appended claims.

I claim: 1. An elevator braking system having an elevator, a channel adjacent the path of movement of the elevator, a chain for supporting the elevator, and a braking device comprising:

two pivot pins connected to the housing adjacent the channel and spaced from each other in a direction generally perpendicular to the direction of the path of the elevator;

two shoes each mounted on and rotatable about a respective pivot pin, each having offset serrated edges, and each positioned within the channel to be engageable with opposite sides of the channel;

a housing connected to the elevator and having a lost motion slot;

a connecter having a connecting pin connected to the housing through the lost motion slot with said slot, connecter, and connecting pin positioned to stop movement of said connecter at a first position with said connecting pin at one end of said slot and at a second position with said connecting pin at the other end of said slot;

an actuator bar, movable to a first and second position relative to the housing and engageable with the eonnecter, positioned to be placed in the first position by said connecter when said connecter is moved to its first position and positioned to place said connnector in itssecond position when said actuator bar is moved to its second position;

a chain connecter linkage connected to the chain and to the connecter to hold said connecter in its first position when the tension of said chain is above a level selected to indicate that said chain is supporting the elevator;

a reset pin on the actuator bar engageable with the shoes to rotate said shoes free of the sides of the channel upon movement of said actuator bar to its first position;

a lip on the actuator bar adapted to engage and rotate the shoes in opposite directions to engage the opposing sides of the channel in an upward direction upon movement of said actuator bar to its second position and thereby stop downward movement of the elevator; and

a spring connected to move the actuator bar to its second position upon decrease in the tension of the chain below the selected level thereby indicating the breaking of the chain. 

